Target template precision is unaffected by target-distractor similarity

Abstract

It is well supported that target templates held in visual short-term memory guide visual search (Desimone & Duncan, 1995; Wolfe, 1994). We investigated how template precision is affected by search context. Following previous research, participants searched RSVP streams for an orange letter and reported its presence or absence (Anderson, 2014). In different blocks, distractor letters were either similar to the target color (red, gold, green and blue) or dissimilar to the target color (white, purple, green and blue). If template precision is affected by search difficulty, accuracy differences should be found between the two distractor conditions. In Experiments 1-3, the RSVP stream consisted of eight frames of four letters each. Targets in Experiment 1 could appear at any location on the 2^nd-6^th frames. Compared to the distractor dissimilar condition, accuracy in the similar distractor condition was significantly worse. This difference, however, may reflect insufficient time for selection and consolidation processes, not template precision. To test this, targets in Experiment 2 appeared on screens 4-8. While subsequent displays may interrupt processing of the 4^th-7^th screens, the 8^th (final) screen allows adequate time for selection and consolidation. Here, a significant interaction was found between distractor color and target position with follow-up tests indicating significantly better performance at the 8^th position in the similar distractor condition. For Experiment 3, additional time was added between each RSVP display to allow selection and consolidation of each display. Although the main effect of distractor color was significant, the accuracy difference between the conditions was greatly reduced. To remove the need for selection processes, Experiment 4 presented a single stream of 16 frames. Accuracy for this experiment did not differ between conditions. The results of these experiments suggest that target identification is limited by selection, consolidation, and comparison processes, but not by template precision.

Meeting abstract presented at VSS 2015